int doNothing(int a)
{
    return a;
}

// 参数数量不匹配，测试编译器是否报错, int c
int sum(int a, int b)
{
    return doNothing(a) + b;  // test of ignoring c;
}

int mainFunc(int arg1, int arg2, int arg3)
{
    int a = 0;
    a = sum(arg1, arg2);
    int b = sum(a, arg3);
    int c = b + sum(b, 1) + 2 + sum(3, b) + 4;
    return c;
}